Superpotential drain



Aug. 30, 1932. c. E. BENNETT SUPERPOTENTIAL DRAIN Filed Sept. 23. 1926 3 sheets-sheet 1932- c. E. BENNETT 1,875,212

SUPERPOTENTIAL DRAIN l Filed Sept. 23, 1926 3 Sheets-Sheet 3 Patented Aug. 30, 1932 UNITED STATES PATENT QFFICE CHARLES E. BENNETT, OF DECATUR, GEORGIA SUPERPOTENTIAL DRAIN Application filed September 23, 1926. Serial No. 137,310.

My invention relates to a superpotential drain, and particularly to an installation appropriate for the protection of power line equipment against injury due to dangerous electrical disturbances.

The object of my invention is to provide a simple, inexpensive and exceedingly efli- .cient unit which will drain the line of dangerous ation, and various novel features of construction and operation hereinafter explained or shown in the accompanying drawin s in whichigs. 1 and 2 are respectively side elevationand plan of a unit in which my invention is embodied in one form;

Fig. 3 is a front elevation thereof;

Fig. 4 is a broken side elevation of the head tank of a unit drawn to a larger scale; and

Fig. 5 is a similar view of the foot tank of a unit.

The layout shown comprises an electrically grounded supporting framework of structural metal, comprising an upright with horizontally extending bracket arms 16 at its upper end. Inasmuch as most power lines are of 3-phase type, the structure is of sufficient extent to accommodate three drain units, one for each phase, properly spaced apart. The drain construction is the same sitive to superpotentials of both high and low frequency. To the stem of the terminal 21 is connected the lead 23 to that phase of the power line which the associated drain unit serves. To the cap of the other gap terminal 22 is electrically connected one end of a metallic supporting bridge 24, the other end of which is mounted on the cap of insullator 25 carried by the rail on bracket arms The drain unit proper, in the form shown, comprises a relatively small head tank 26, and still smaller foot tank 27, both of metal, and one or more lengths of insulating tubing 28 connected at opposite ends to the head and foot tanks 26, 27 respectively, and opening to their interiors. Appropriate liquid electrolyte 29 fills the tubing 28, which communicates with the bodies of electrolyte in the head and foot tanks. Inasmuch as these tanks are of metal and the contained electrolyte is in contact therewith, a current path is afiorded by the electrolyte between the head and foot tanks through the insulating tubing 28. Head tank 26 is carried by and in electrical contact with the bridge 24. Foot tank 27 is carried by and in electrical contact with cross bar of the grounded frame. Current flowing across the gap 21, 22 therefore follows the insulator cap 20 to bridge 24, thence through the wall of the head tank 26 to the contained electrolyte therein, thence down through the electrolyte in tubing 28 to the body of electrolyte in the foot tank 27, thence through the wall of the latter to ground 31, through the cross bar 30 and frame 15.

The details of shape, form and construction of the drain unit are subject to so many variations, while still attaining the advantages of my invention, that even the general features above mentioned are to be understood as illustrative of merely a satisfactory construction by which my invention may be practiced. In Figs. 4 and 5, the details of this illustrative construction are indicated.

Referring to Fig. 4, in which the head tank 26 is shown on a larger scale, the body of the tank is indicated as formed from a metal cylinder (of brass, for example), closed at its upper end by a disc 32 wlth removable annular flange screw plug 33 closing a fill aperture by which electrolyte may be introduced into the unit. At its opposite end the tank is closed by a disc 34 which carries one or more screw nipples 35 for the reception of the upper end of the tubing 28. Adjacent its end each length of tubing is provided with a strong 36 which overlies the end of the screw nipple 35 against which the flange is firmly clamped by a screw cap 37, not only to support the tubing from the tank, but to seal the joint against leakage, even under pressure.

Exteriorly the head tank may be provided withradiation fins to assist in maintaining the tank and its contained electrolyte cool, although these fins are of no practical importance except under service conditions of very great and prolonged severity. The tank also carries a gauge 38, at the upper end of which is a vent passage 39 to prevent the building up of dangerous pressure within the unit.

At the mouth of the passage 39 is freely seated a knurled ball 40, which while preventing evaporation of electrolyte, aifords sufiicient inlet for air to relieve any partial vacuum which may tend to occur following condensadiaphragms, plates, spaced above the electrolyte, confine tion of steam formed within the unit on functioning.

' Interiorly the tank may be provided, above the level of the electrolyte, with one or more 41 perforated at- 42. These air cushions which prevent shock on the suds den upward displacement of electrolyte into 7 the tank 26 when the unit functions. The

staggered arrangement of the apertures 42 also prevents the electrolyte from being expelled through the vent 39.

The foot tank 27 (Fig. 5) comprises a metal cylinder, also preferably of brass, but shorter thanthe head tank 26. At its upper end it i s'closed by a plate 43 with screw nipples 44, similar to those of the plate 34 of the head tank 26, for connection with the lower end of the tubing 28.; Its, bottom plate 45 also carries a screw plug 46 closing, in this a drainage hole. Thetubing which connects the head and foot tanks is of small bore and of strong walled, non-shattering, non-combustible (under operating conditions) insulating mate- 'rial such as low grade rubber compositlon.

Strength of wall is necessary to withstand internal strains incident to the vaporization of electrolyte within the tubing when the unit functions. The non-shattering characteristic is desirable since in case of rupture no dangerous scattering of broken fragments occurs. Non-combustibility is important,

since on the functioning of the unitan arc is drawn Within the tubing, and while the vapor and liquid conditions therein are inimical to combustion, nevertheless the tubing is momentarily subjected to great heat. Its insulating characteristic is'of course necessary .ing to assume various positions (for example,

the angular location of the foot tank 27 with respect to the head tank), and also to yield under the stress of rapidly displaced liquid within the tubing which occurs on functioning of the unit. 7

In length the tubing is preferably such that the distance therethrough betweenthe bodies of electrolyte in the head and 'foot tanks materially exceeds the normal arc-over gap spacing at line voltage. This insures extreme rapidity of operation, since on are formation within the tube, the arc plays upon a relatively small body of electrolyte already highly heated by current flow therethrough, and vaporization is practically instantaneous as also. the attenuation of the arc to extinction. This characteristically rapid operation is not attained when the tubing is soshort that the arc plays between the relatively cold bodies of electrolyte in the tanks.

At the end of the tubing connected to the foot tank 27 I provide tubular extensions 47 which project below the surface of the electrolyte in the tank 27. These extensions may be of metal tubing having a bore which exceedsthe bore of the tubing 28. The most restricted cross-sectional 5 area of the electrolytic path connecting the head and foot tanks 26 and 27 is thus definitely located within the tubing 28. The, extensions 47 serve merely as liquid seals which insure the maintenance of a'cushioning air chamber 48 above the level of the electrolyte in the foot tank 27.

The electrolyte may be of any suitable character. It should besuch that, onvaporization it does not liberate a free conducting gas. Its conductivity must'be such that it will freely drain the line of superpotential. Preferably it is non-freezing, even at low winter temperature. I have found calcium chloride of a concentration in the neighborhod of 27 B. to satisfy these importantconditions.

When a line disturbance is such as to cause a break down of the gap 2l-22, the current -both the superpotentialand the normal dynamic currentfiows through unit to ground. This current, in passing through the electrolyte in the small bore tubing 28, vaporizes the electrolyte by the heat generated, thus breaking the continuity of the electrolytic path and interposing, at the break, a resistant vapor under pressure, as well as the unstablesurfaces of the electhe drain is so impeded by these conditions that the arccannot persist at the-gap 21, 22, the drain line is opened and the current caused to follow its normal circuit path in the power line.

When the electrolyte is vaporized at some initial point in the'tubing 28 by the current flow, the pressure of the vapor tends to displace upward into the head tank 26 the portion of the liquid in the tubing above the break point, and also to displace down ward into the foot tank 27 the portion of the liquid below the break point. This expulsion of liquid in opposite directions by the vapor, is sudden and violent. The quantity of liquid displaced, however, is small, due to the small bore of the tubing, and the head and foot tanks have ample capacity to receive it. The air cushions above the surface of the electrolyte in both of the tanks prevent sudden strain on the tanks,'and moreover, excessive pressure is relieved at the vent 39.

As soon as the drain line opens, the vapor condenses, forming a partial vacuum within the tube. This condition, coupled with the pressure on the surfaces of the electrolyte in the head and foot tanks, causes the liquid to refill the tubing almost instantly. The electrolytic path through the unit is thus reestablished in readiness for a succeeding operation.

It has been found that by using an interrupter or drain constructed according to the description above, the time, for an interruption has been cut down to as few as two cycles, whereas heretofore from ten to fifteen cycles have been required.

lVhile the tubing is thick walled and consequently mechanically strong, it is possible that under conditions of very violent discharge, sufiicient pressure may be built up to cause its rupture. Should this occur the electrolyte is expelled, thus automatically opening the drain line. To repair the unit it is merely necessary to renew the burst tubing and replace the lost electrolyte. This may be safely accomplished if the normally closed switch 49 is temporarily opened. Alternatively, the head tank may be detachably supported, after the fashion of a cartridge fuse, by contact clips on the bridge 24, or its equivalent, so that it may be readily removed by means of a switch stick or the like.

The number and length of the tubes 28, and the diameter of their bores, may be varied as necessary to insure prompt functioning at various line voltages. This can also be regulated by varying the conductivity of the electrolyte. A definite break point within the tubing, at which vaporization is initiated, may be established by compressing the tubing at a desired point in its length, thus further constricting the bore in that area. I

ticularly have found this unnecessary, however, to very rapid functioning.

The economy of construction will be realized when it is considered that for a 75,000

volt unit I have found it sufficient to use a head tank of only two gallons capacity having an overall diameter of about 5 ,4 inches, and a length ofapproximately 27 inches; a foot tank of less than half the same capacity, approximately 12 inches overall length; the tubing consisting of two lengths of approximately 27 feet each, an overall diameter of 1 inch, and a bore of something less than inch each.

Emphasis mayalso be placed upon the fact that the tubing material is of such character that it is not injured by sudden temperature changes incident to the sudden heating, followed by the sudden chilling which occurs when the apparatus functions and then resets. Porcelain, glass, hard rubber and like refractories, shatter under such conditions. Even when jacketed by fluid the sudden heating of the inner wall of such shattering refractories, sets up internal stresses which cause fracture.

While I have described my invention parwith reference to a superpotential drain, certain features are appropriate to equipmentof other types, such as switches, fuses, etc., and these uses or adaptations are contemplated by me, where appropriate, within the scope of the following claims.

I claim 1. A superpotential drain comprising a conduit of yieldable insulating material, a supply of electrolyte therein, and means for leading superpotential current to the electrolyte in the conduit to cause vaporization thereof as the result of current flow therethrough.

'2. A superpotential drain comprising a conduit of yieldable insulating material means for maintaining a supply of vaporizable electrolyte therein, and means for leading superpotential current to the electrolyte in the conduit to cause vaporization thereof as the result of current flow therethrough.

3. A superpotential drain comprising a flexible conduit of non-shattering, rubber composition, a supply of electrolyte therein, and means for leading superpotential current to the electrolyte in the conduit to cause vaporization thereof as the result of current flow therethrough.

4. A superpotential drain comprising a circuit with arcing electrodes and a conduit of insulating material affording a constricted passage of greater length than arc-over spacing at normal potential, a supply of electrolyte in said conduit, said electrolyte liberating, on vaporization, a poorconductor of electricity, and means for leading superpotential current to said electrolyte to cause vaporization thereof as theresultof current flow therethrough. r r

v5. A superpotential drain comprising a circuit with arcing electrodes and spaced metallic. conductors, andmeans providing an electrolytic path of restricted cross-section therebetween, said path being of greater length'than arc-over spacing at normal potional and said means comprising an electrolyte, which, on vaporization, liberatesa poor conductor of electricity. V r

6. A superpotential drain comprising a circuit .with arcing electrodes and spaced bodies of electrolyte interconnected by an electrolytic path of restricted cross-sectional area and of a length exceeding arc-over spacing at predetermined normal current potential, the electrolyte of said path liberating, on

vaporization, a gas which is not freely conducting;

7. A superpotential drain comprising-a circuit with arcing electrodes and spaced bodies of electrolyte interconnected by an electrolytic path of restricted cross sectional area and of a length exceeding arc-over spacing at predetermined normal current potential, together-with containers only partially filled rent to ground through said electrolyte in the tube. 1

13. In a superpotential drain, a grounded supporting structure, a pair of spaced metallic containers mounted thereon, one of said containers being insulated from, and the other in electrical connection with, said structure, a tube of insulating material establishing connection between said containers, electrolyte in said tube and containers, said electrolyte libcrating a resistant gas on vaporization, and

means for leading superpotential current to the electrolyte in said insulated container to establish a ground connection through the electrolyte in the tube and other container to ground.

14:. A superpotential drain comprising a tube of yieldable and non-shatterable insulating material having a bore of substantially for maintaining a body of vaporizable electrolyte in said tube and means for leading superpotential current to said electrolyte.

In testimony whereof I have signed my name to this specification.

CHARLES E. BENNETT.

by said spaced bodies of electrolyte to accommodate electrolyte expelled thereto from said an element thereof, a yieldable tube of noninflammable soft rubber composition adapted to contain vaporizable electrolyte, together with a container for a body of the electrolyte opening to one end of the tube;

11. A superpotential drain comprising as an element thereof, a yieldable tube of noninflammable soft rubber composition adapted to contain vaporizable electrolyte, together with independent, spaced containers for bodiesof electrolyte opening to opposite ends of the tube.

12. In a superpotential drain, a ground connection comprising a pair of spaced metallic containers, and a tube of yieldable insulating material interconnecting the same, electrolyte in said tube and containers, said electrolyte liberating a non-freely-conducting gas on vaporization, together with electrical 7 connections for leading superpotential ouruniform restricted cross-sectional area, means 

